1. Field of the Invention
This invention is in the field of food products and, more particularly, directed to a method for producing a dehydrated food product, including whole cooked bean (and other such similar) products in such a way as to preserve the structural integrity of the bean which, in turn, helps provide a food product having significantly enhanced texture and quality.
2. Background
The prevalence of fast-food style establishments in recent years has been accompanied by an increased demand for reconstitutable food products, such as, for example, dehydrated refried beans. From an economic point of view, such products have several advantages. For example, each establishment can buy and store the product in bulk quantities without the risk of spoilage. Also, since the product is normally reconstituted in a matter of minutes by adding only water, there are savings in time, energy, and labor associated with the use of these products. Finally, since there is no need to continually prepare the food product in the conventional manner (i.e., to make the food fresh, and on a daily basis), there is also no need for each establishment to keep extra equipment (e.g., cookware, etc.) on the premises. As such, methods have been devised to produce reconstitutable food products that, ideally, could be prepared very quickly, and would have the taste, texture, and appearance of their conventionally-prepared counterparts.
Current methods and apparati for producing such food products and, more specifically, refried bean products, require that one consider various factors. For example, to satisfy the requirement that the raw beans be mixed as they are hydrated and, also, as they are cooked, a number of the methods presently known employ rotating vessels. Vessels that rotate are used so that the beans can be contacted with a small amount of water that is diminishing as the water is absorbed by the beans. Controlled amounts of water are used during the cooking process in hopes that at the end, little or no water remains—only the cooked, hydrated beans. This is difficult to achieve, and the art has searched for various methods, as excess water can result in yield loss (some of the beans will dissolve into the water) and/or a pasty product that is difficult to further process and dry. Merely placing the beans in water has other shortcomings. For example, such a method can result in some beans becoming too soft, while others do not become properly hydrated. Further, prior art vessels are generally quite bulky, which not only translates into added and more-frequent maintenance requirements, but also makes it more difficult to achieve economies of scale. Further still, generally, in many prior art vessels only a small amount of beans can be treated. In other words, to achieve the benefit of a small water-to-bean ratio, rotating vessels of particular configurations and having limited capacities were used. Even then, it is difficult to control the water absorption into the beans.
Yet other shortcomings relate to the starting materials that are used. In a typical prior art process for preparing refried beans, dry, raw beans are placed into the vessel, and a small quantity of water is added. Unless the vessel rotates, the beans on the top of the pile could absorb a different amount of water as compared to the beans at a position lower down. Further, as the water level in the vessel decreases, yet further non-uniform water absorption throughout the beans could result. It is known that raw beans typically have an initial moisture content in the range 6%–14%. However, current methods have difficulty using a batch of raw material that spans this entire range because the disparity in initial moisture levels exacerbates the variations in water absorption during hydration with small amounts of water, which would, in turn, result in a non-uniform final product. As such, in order to use many prior art methods and apparatuses, the practitioner is limited to using rotating vessels and to batches of raw materials, each of which falls within a small sub-group of initial moisture-content ranges (e.g., those in the 6–8% range, or those in the 10–12% range, etc.).
In the current state of the art, there are also disadvantages associated with the end product itself (e.g., with the dehydrated bean product). For example, even though one goal of dehydrated food products is to allow for rapid water take-up at reconstitution, this goal is only partially met in current dehydrated bean products. As is known in the art, most current methods produce products that are either in the shape of small pellets or in the shape of flakes or in the shape of fine powder. In the case of pellets, because of the way in which the final product is prepared, typically only a small portion of the surface area of each pellet (i.e., typically, the two ends of each pellet) provides areas through which water can easily be absorbed; the remainder of the pellet's outer surface is inefficient in absorbing water. Flakes, on the other hand, due to their method of manufacture, have a harder outer surface and are generally treated with oil on their surface, which is a water repellent, so that water take-up upon reconstitution is actually slower than it may be otherwise. Therefore, in both cases, water absorption rates are not optimal.
Moreover, upon reconstitution, many of the dehydrated products currently available turn into paste-like, or other similar, uniform compositions, where there is generally a lack of texture in the food. This is especially true with methods and apparatuses that produce a granular, rather than a pelletized, or flake-like, dehydrated product. In addition, regardless of the actual shape and form of the final product, there is no simple provision in existing methods and apparatuses for varying (i.e., custom making) the texture of the final product as desired.
Reference is made to U.S. Pat. Nos. 4,676,990, 4,735,816, and 4,871,567 as further examples of the prior art. These references illustrate various bean-making processes, but all have a number of shortcomings. For example, in the '990 patent, a pelletized product is produced by particularized processing steps and related apparatus. In the '816 and '567 patents, a thin, flake-like product is produced by means of yet other particularized processing steps and apparatus. These processes are complicated and the final products are only marginally close to refried beans made to have a pleasant texture with a desired amount of bean particulates.
To address some of the issues relating to the lack of adequate texture in the reconstituted food, attempts have been made in the prior art to add dehydrated whole beans to the aforementioned products. However, such attempts have been met with difficulties as dehydration of cooked whole beans has generally been accompanied by a considerable amount of “bird mouthing”.
Bird mouthing, also referred to as “butterflying”, is a phenomenon wherein the whole bean splits along its two halves and opens during the dehydration process. It is believed that bird mouthing is caused by a differential rate of drying between the bean skin and cotyledon, such that, during the dehydration process, the bean skin dries more rapidly than the cotyledon, and thus, contracts (a condition which is referred to as “case hardening”). As dehydration continues, the slower-drying cotyledon develops internal vapor pressure to an extent where the pressure ruptures the skin and causes bird mouthing.
Reference is made to U.S. Pat. Nos. 3,290,159 and 4,871,567 as examples of the prior art's attempts to reduce the amount of bird mouthing in dehydration of whole beans. For example, the '159 patent discloses a two-stage dehydration process, wherein the first stage involves a slower moisture-removal process, and the second stage involves a more rapid dehydration process. Both stages of the disclosed methodology are directed to drying using conventional air dryers. Similarly, the '567 patent discloses a dehydration process comprising two or more “stages”. However, in contrast to the '159 patent, the '567 patent teaches a method involving incremental decreases, rather than increases, in the amount of heat supplied during the dehydration process. Nevertheless, neither methodology seems to have resolved, to an appreciable degree, the problem of bird mouthing.
An additional drawback associated with the process disclosed in the '159 patent is that, in order to be effective, the process calls for slow drying rates. Such slow drying rates translate into relatively long drying times (e.g., on the order of 4–6 hours) which, in turn, result in low levels of throughput per unit time. Similarly, the process disclosed in the '567 patent calls for an initial period of high-humidity drying which, again, results in longer drying times. This is especially true when convective heating is utilized to dry the beans since convective dehydration efficiency drops off drastically during the latter stages of drying particulate material when moisture diffusion from the center of the particle controls the drying rate.
Food manufacturers have also used equipment and/or forms of energy other than conventional air dryers to produce dehydrated food products. In this regard, reference is made to U.S. Pat. Nos. 4,073,952 and 6,197,358. The '952 patent discloses a method of making dehydrated potatoes, wherein the method includes drying pieces of potato by exposing them simultaneously to microwave energy and to hot air. The hot air is enriched with moisture to maintain an average humidity of at least 83% in the oven during most of the drying period. In addition, about 10–50% of the energy used for drying is provided by moisture-enriched air that is heated to between 75 and 255° F. and, typically, to 100–150° F.
However, being unrelated to the production of dehydrated bean products, the '952 patent does not address bird mouthing at all. Rather, it teaches a combination microwave/hot air drying process in order to minimize discoloration and loss of flavor for potato pieces. Similarly, the '358 patent is related to a process in which microwave energy may be used during the production of dehydrated potato products, but not during the drying step.
The features and advantages of the present invention will become more apparent through the following description. It should be understood, however, that the detailed description and specific examples, while indicating particular embodiments of the invention, are given by way of illustration only and various modifications may naturally be performed without deviating from the spirit of the present invention.